Sue is Justin's childhood friend. She often tries to act like an adult and constantly encourages Justin to do so as well. Sue is energetic, knowledgeable and shows wisdom well beyond her years, despite this she occasionally doesn't take situations as seriously as they should be. After losing both her parents, she was taken in by her aunt and uncle and regularly visits Justin and his mother, Lilly for company.

Sue is Justin's closest friend, and she is often seen tagging along with him on "adventures". Sue's parents died when she was only an infant, at which time her aunt and uncle took her in as her legal guardians. Because of this, Sue is extremely mature and responsible for her age. She is often credited for acting more grown-up than Justin, even though she is at least six years younger. At a young age, Sue became used to eating her meals with Lilly and Justin at their house, much to the approval of her aunt and uncle. She tries to act as Justin's responsible guardian, often advising him on manners and work duties. Even she agrees that Justin could not carry out his adventures without her assistance. She often purposefully oppresses her inner childhood feelings in order to appear more grown-up. Because of this, she resents being called a child or a kid. At some point in time, she inherited the creature known as Puffy from Justin, which was actually a creature his father discovered on his adventures. They've become so accustomed to each other that Sue actually uses Puffy in battle. The sprite of Sue can often be seen twirling Puffy like a baton in order to conjure up a spell or to throw him to damage the enemy.